This paper describes a computer-based, dynamic positioning system for floating vessels. The system is based on a detailed mathematical model of vessel motion in response to forces from thrusters, wind, waves and water current. The system uses a Kalman filter for optimal estimation of vessel motions and environmental forces from wind, waves and current. The control system is based on feedback from the motion variables where the oscillatory, wave-induced component is removed by the estimator. Feedback from the water current estimate provides the integral action of the system and feed forward from the wind force estimates are implemented. Simulation results and recordings from actual operation of the system indicate an excellent system performance

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This paper describes a computer-based, dynamic positioning system for floating vessels. The system is based on a detailed mathematical model of vessel motioninresponse to forces from thrusters, wind, waves and water current. The system uses a Kalman filter for optimal estimation of vessel motions and enviromental forces from wind, waves and current. The control where the oscillatory, wave-induced component is system is based on feedback from the motion variables removed by the estimator. Feedback from the water current estimate provides the integral action of the system and feed forward from the wind force estimates are implemented. Simulation results and recordings from actual operation of the system indicate an excellent system performance. Reference is given to installations made on actual vessels.

Numerical simulation of dynamic positioning (DP) in ice is a novel research topic that has potential in many industrial and scientific applications. This paper reviews some challenges associated with numerical ice modeling and presents a classification of approaches for modeling the ice loads in DP simulations. The approaches are classified into three groups: empirical and statistical models, experimental data series methods, and physically based modeling. The strengths and weaknesses of the approaches are summarized, and recommended uses are outlined in this paper. In addition, a novel, nonsmooth, discrete element model of a DP vessel in managed ice is presented. The model was used to perform a numerical multibody simulation of a series of model tests with a conceptual Arctic drillship on DP in managed ice using the commercial physics engine Vortex. The numerical model simulated the ice basin, the DP vessel, the managed ice, the surrounding fluid, and their interactions. Comparison of the simulation results with experimental data showed that for head-on ice drift, the numerical model reproduced the experimental results reasonably well. However, for higher ice drift angles, discrepancies between the simulation results and the model testing data increased considerably. Possible reasons for the discrepancies are discussed in the paper, along with suggestions for future research. To the best of the authors’ knowledge, both the classification of various approaches for simulating DP in ice and the high-fidelity numerical DP model are novel and have not been published previously.

DYPIC -Dynamic Positioning in ICE -is an international research and development project partially financed by the national research agencies of Germany, Norway and France. This 3-years initiative (2010-2012) focused on the development of Dynamic Positioning (DP) technology for the Arctic environment. The projects' backbone was formed by two extensive experimental campaigns performed in 2011 and 2012. This paper summarizes the work performed within the project and spotlights the technical and scientific findings emerged from it. Special attention is payed to two facets of the project: the design of experimental devices, systems and setups for ice tank testing including the development of a dynamic positioning system for model basin facility, and the development of an ice basin numerical simulator. Finally, the opened perspectives are discussed with a special focus on the operational matters.